Define pie operator menu position
You are showing two different menus, one in object mode the other in edit mode, the different names above the centre circle indicate they are using different code - the name comes from bl_label of the menu class.

While the order that items appear does seem odd at first, there is an order to the madness. The primary design is to have one operator at each position, starting from the left, then the right, bottom, top, then the top diagonals and the bottom diagonals.

Run the following script in the text editor and have a look at the items positions, then uncomment one of the lines between operators and see how it effects the layout of the menu, repeat for each commented line.

import bpy

class VIEW3D_PIE_template(bpy.types.Menu):
    bl_label = "Render"

    def draw(self, context):
        layout = self.layout

        pie = layout.menu_pie()
        pie.operator("render.render", text='one')
        #pie = pie.column()
        pie.operator("render.render", text='two')
        pie.operator("render.render", text='three')
        #pie = layout.menu_pie()
        pie.operator("render.render", text='four')
        #pie = pie.row()
        pie.operator("render.render", text='five')
        pie.operator("render.render", text='six')
        #pie = layout.menu_pie()
        pie.operator("render.render", text='seven')
        pie.operator("render.render", text='eight')

if __name__ == "__main__":
    try:
        bpy.utils.unregister_class(VIEW3D_PIE_template)
    except:
        pass
    bpy.utils.register_class(VIEW3D_PIE_template)

    bpy.ops.wm.call_menu_pie(name="VIEW3D_PIE_template")